The invention relates to a method and device for operating a head-up display of a vehicle and to an image determining system for the head-up display.
In a motor vehicle, technical information, for example the current vehicle speed, the engine rotational speed or the oil temperature, as well as traffic and navigation data, are provided to the driver during a trip. The information is usually displayed on an instrument panel. When reading the displayed information from the instrument panel a driver is distracted at least for a short time from the traffic situation. Head-up displays make it possible to display information directly in the field of view of the driver on the windshield of the vehicle. In this way, information content can be comprehended while simultaneously the road conditions remain in the driver's field of view.
Modern head-up displays generate a virtual image which, for the driver, appears to lie at a certain distance before the windshield, for example at the end of the hood.
Modern vehicles increasingly have driver assistance systems. By means of these driver assistance systems it is possible, for example, to recognize and locate objects, such as pedestrians, other vehicles and traffic signs. The head-up display can be used for optically signaling information with respect to the recognized objects.
The object of the invention is to provide a method and a device for operating a head-up display, as well as an image determining system, which makes a contribution in that information can be signaled optically with a high quality by way of the head-up display.
This and other objects are achieved according to the invention by a method for operating a head-up display for a vehicle, wherein on the basis of a predetermined three-dimensional vehicle environment model which is determined on the basis of at least one first image of an image sequence and which comprises an object which is detected in the first image and has a predetermined resulting absolute position and/or a predetermined resulting position with regard to the vehicle, a corrected display image is determined. The corrected display image is determined on the basis of a currently captured second image of the image sequence, which is captured, for a predetermined period of time after the first image and which comprises the detected object. The corrected display image comprises at least one graphical element, which represents the detected object and is determined in such a way that it is suitable to be projected onto a predetermined display field of the head-up display, so that the at least one graphic element is perceived by a viewer of the display field from a predetermined viewing position with direct reference to the real environment of the vehicle.
According to a first aspect the invention is characterized by a method and a corresponding device for operating a head-up display. In this connection on the basis of a predetermined three-dimensional vehicle environment model and on the basis of a currently captured second image of the image sequence, a corrected display image is determined. In this case the vehicle environment model is determined on the basis of at least one first image of an image sequence and comprises an object which is detected in the first image and has a predetermined resulting absolute position and/or a predetermined resulting position with regard to the vehicle. The second image is captured a predetermined period of time after the first image and comprises the detected object. The corrected display image comprises at least one graphic element, which represents the detected object and is determined in such a way that it is suitable to be projected onto a predetermined display field of the head-up display, so that the at least one graphic element is perceived by a viewer of the display field from a predetermined viewing position with direct reference to the real environment of the vehicle.
This advantageously makes it possible to correct latency and/or delay times which may occur during determination of the original display image.
This can advantageously make a contribution in that information can be signaled optically with a high quality by way of the head-up display. The graphic element can be displayed in a contact-analog manner. In head-up displays a distinction is made between contact-analog and non-contact-analog display. Contact-analog forms of display enhance the environment perceived by the driver by superimposition of artificially generated scenery. The information is displayed with a direct reference to the environment.
Processing times and/or latency times which occur on the basis of a transmission of image data in the vehicle and/or the determination of the original and/or of the corrected display image, in particular on the basis of complex algorithms for object recognition and/or for object location and/or motion prediction of the determined objects, can be compensated for. Thus it is advantageously possible for the representation of the at least one graphic element on the head-up display to be precisely positioned, or at least very precisely positioned, and without time lag, or at least with only very little time lag. A further advantage is that simpler algorithms can be used for the motion prediction and thus more efficient processing is possible.
A signaling signal for control of the head-up display for optical signaling of the corrected display image can be determined on the basis of the corrected display image. The signaling signal can represent respective pixel values of the corrected display image.
In an advantageous embodiment of the first aspect, the corrected display image is determined on the basis of an original display image having the at least one graphic element which represents the detected object of the detected first image. The original display image is determined on the basis of the predetermined three-dimensional vehicle environment model in such a way that it is suitable to be projected onto the predetermined display field of the head-up display, so that the at least one graphic element is perceived by the viewer of the display field from the predetermined viewing position with direct reference to the real environment of the vehicle. This can advantageously make a contribution to determining the corrected display image simply and quickly, since in this case an image synthesis, also referred to as rendering, has already taken place and pixel values of two-dimensional images can be compared and/or evaluated.
In a further advantageous embodiment of the first aspect, a detail of the second image which comprises the at least one object is determined on the basis of a determined intrinsic movement of the vehicle, and the corrected display image is determined on the basis of the detail of the second image. This has the advantage that it may be sufficient to transfer a smaller amount of image data to be transmitted and/or to be processed for determining the corrected display image. The detail of the second image may correspond to a detail which the corrected display image represents.
In a further advantageous embodiment of the first aspect, the second image comprises a stereo image and the detail of the second image is determined on the basis of a position of the vehicle driver and a capture position of the second image. This has the advantage that a viewing angle-corrected detail of the second image can be used for determination of the corrected display image. This advantageously enables a high-quality perspective representation of the at least one graphic element on the head-up display, so that from the viewpoint of the driver of the vehicle the representation of the at least one graphic element takes place without distortion.
In a further advantageous embodiment, a current first position of the at least one object is determined on the basis of the second image and/or of the detail of the second image. The corrected display image is determined on the basis of the first position and a second position which has the at least one object in the vehicle environment model. This enables an efficient determination of a position offset of the at least one object and thus an efficient determination of the corrected display image.
In a further advantageous embodiment of the first aspect, a characteristic image feature of the at least one object is determined on the basis of the second image and/or of the detail of the second image and the corrected display image is determined on the basis of the image feature. This has the advantage that the second image and/or the detail of the second image can be analyzed very simply and quickly. Thus the determination of the corrected display image can take place very efficiently and quickly. In this case the respective image feature may comprise a 1-bit graphic.
In a further advantageous embodiment of the first aspect, the characteristic image feature comprises a respective border of the at least one object. This enables an efficient calculation of the image feature.
In a further advantageous embodiment of the first aspect, a color and/or brightness of the graphic element in the corrected display image is adapted on the basis of a characteristic image texture of the at least one object in the first image and/or the second image and/or the detail of the second image. This has the advantage that the color and/or the brightness of the graphic element can be adapted on the basis of a color and/or brightness of the at least one object.
According to a second aspect, the invention is characterized by an image determining system for a head-up display. The image determining system comprises an evaluation unit which is designed to detect at least one predetermined object and to determine a position of the at least one object on the basis of predetermined image data of a captured first image of an image sequence. Furthermore, the image determining system comprises a prediction unit which is designed to determine an absolute movement and/or a relative movement of the at least one object with reference to the vehicle on the basis of at least one predetermined sensor signal. The image determining system comprises a scene unit which is designed to determine a three-dimensional vehicle environment model on the basis of the at least one first image of the image sequence and the determined absolute and/or relative movement of the at least one object. Furthermore, the image determining system comprises a device for operating the head-up display according to the first aspect.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.